The present invention relates to an iontophoresis system applied percutaneously or trans-mucosally, and in particular to a portable iontophoresis system.
Iontophoresis is a percutaneous absorption-promoting system which employs electricity for external stimulation. Its principle is such that skin barrier permeability of drug molecules is promoted by movements of positively-charged molecules from an anode to a cathode and those of negatively-charged molecules from the cathode to the anode in an electric field mainly produced between the anode and the cathode by power supply [refer to Journal of Controlled Release, Vol. 18, pages 213 to 220, 1992; Advanced Drug Delivery Review, Vol. 9, page 119, 1992; and Pharmaceutical Research, Vol. 3, pages 318 to 326, 1986].
Thus, in iontophoresis, an anode and a cathode are provided in pair and a current is generated between the anode and cathode, thereby moving a drug. In recent years, a constant current unit is employed so that a current can be maintained at a predetermined value irrespective of an impedance difference due to individual difference. This constant current unit can keep a drug delivery rate constant irrespectively of impedance because the drug delivery rate correlates with a current quantity. A unit of such type is disclosed in Japanese Patent Laid-Open Publication No. 5-245214, for example. In addition, a unit for controlling a drug supply rate with a program as required is disclosed in Japanese Patent Laid-Open Publication No. 7-124265, for example.
In the meantime, in order to achieve a small iontophoresis system suitable to be portable, in particular, it is required to minimize the number of circuit parts of a power supply apparatus and miniaturize the unit. Among them, in particular, it is desired to reduce a battery incorporated in the power supply apparatus in size and in weight. When a small battery is employed, in general, frequent battery replacement is required because of its small battery capacity, which requires a user to do cumbersome operation of battery replacement, and thus, is not preferable. In addition, it is desirable that battery replacement can be avoided as far as possible from an economical aspect or an environmental aspect including disposal of used battery.
Further, another problem with a portable power supply apparatus includes circuit malfunction caused by faults of components. At the time of designing a circuit for the power supply apparatus, safety is taken into account to avoid such discrepancies that, a high output current exceeding a set level is generated or an output cannot be stopped completely when it must be stopped, even if the above malfunction occurs. For example, such a system is disclosed in National Publication of International Patent Application No. 8-505541.
However, when any of the parts constituting a power supply apparatus fails, influence on operation of the power supply apparatus greatly differs depending on which of these parts fails. When a power supply apparatus itself cannot identify a failure, a user may use the failed unit repeatedly until the failure is found. In order to overcome these problems, a large-scale circuit is generally required, which acts against reductions in size and weights of a power supply apparatus.
In view of the foregoing circumstance, an object of the present invention is to provide a small and light iontophoresis system with superior usability.
The present inventors made efforts earnestly to reduce an iontophoresis system in size and weight. As a result, they found out that if a small secondary battery is employed for a power supply and at least one of charge terminals for charging the battery is also used as an output terminal, a small and light-weight iontophoresis system with superior usability could be used, and accomplished the present invention.
An iontophoresis system according to the present invention comprises a power supply apparatus having a chargeable battery and a plurality of output terminals and a preparation which is connected to the output terminals of the power supply apparatus and which is adopted to administer a drug percutaneously or trans-mucosally, wherein at least one of the output terminals of the power supply apparatus is also used as a charge terminal for charging the battery. Here, a secondary lithium battery, for example, is employed as a chargeable battery.
An iontophoresis power supply apparatus according to the present invention comprises a chargeable battery, a plurality of output terminals for outputting electric energy from the battery, and a charge terminal for charging the battery, wherein at least one of the output terminals is also used as a charge terminal. In addition, the present iontophoresis power supply apparatus preferably comprises a power supply monitoring portion that monitors a battery voltage and gives warning when the battery voltage becomes a predetermined value or lower. Further, the present power supply apparatus preferably comprises a control portion for controlling power supply of electric energy outputted from the output terminals. The control portion is adopted to record a power supply state of electric energy or to externally incorporate a program for power supply control of electric energy.
An iontophoresis charger according to the present invention is adopted to charge a battery of the iontophoresis power supply apparatus. This charger comprises an operational check portion which performs operational check of the power supply apparatus based on an inputted power supply record of the electric energy outputted from the power supply apparatus. This charger can comprise a display portion for displaying a power supply record of the power supply apparatus. In addition, the charger may comprise a program storage portion that stores a program for power supply control of the power supply apparatus.